Regulating system



March 2o, 1951` A J. Mom mL 2,546,039

REGULATING SYSTEM Filed April e, 194e mgl.

Inverjtors James Mof, Wiliam SGVaFFBakeV;

bym The r-Attorn @y Patented Mar. 20, 1951 'Y REGULATING SYSTEM vJames/Muir and 'Wiliiam S. Graff Bakerg Rugby,

*"England, assignors, to General EiectricigCompany, a corporation of NewYork Application April r6, 1946, Serial No. 660,032

InGi-eat Britain August v21, 1945 6 Claims. 1

Ourinvention relates to 'regulating systems .and more-particularly toelectron tube regulators utilizingv a source of :referencepotentialwhich varies in voltage'in accordance with ambient temperature.

In a common system for regulating a load characteristicv as, forexample,v load voltage, a `series 'connected electron discharge deviceis placed between aV unidirectional voltage source and a load fc'ircuitand the grid bias controlledin accordance With output voltage. This isaccomplished by providing .a current. path across the supply .voltagesource comprisinga resistance, anV electron dischargedevice;` ande asource of reference voltage in seriesrelation. The grid' ofthe .latterdevice is connected toa potentiometer ,connected across `theload-circuit. so `that theV total effective grid bias applied thereto isdetermine-d bythe difier- 'ence` between the selected portionofloadvoltage andthe constant reference voltage.

ATheabove' mentioned voltage regulator constitutesia .negative feedbacksystem wherein the 'difference lbetween outputvoltage andthe desiredregulated value'is fed back to the control circuit lin Adegenerativephase. Inasmuch as the system always tends to cause the value of thisdifference'voltage to approach a specic value, the 'system outputisinfluenced 'byany changes' in VtheY voltage of the reference source.Since the reference voltage sourcesnormally used' have some' variationYin l voltage `with temperature, temperature changes produce a variationin regulating :output voltage. In particular, in the .case ofgasdischarge devices ordinarily used as a sourcev of reference voltagel avoltage' variation Withftemperature of the order of ".0005 per Y"C.takes pla-ce -Whereas batteries used for this purpose have a' voltagevariation with tem erature ofthe order of '.000l5rper C.

It is theobject .of our invention -to provide regulator-Which operatessubstantially independently ottempera-ture variations at thesource ofreference potential.

It is a further object of our invention to provide .and improvedregulator wherein thel .effects of temperature variationsat :the gasdischarge tube or battery used as a source of reference potential arecompensated by other circuit changes.

l In general,V our invention resides in providing a temperaturesensitive-resistance physically disposed tovpartake-ofthe-,temperatureof the source of :reference voltage andy electrical-ly-.connected .to-introduce a compensating voltage 'sufficient-to .balance.thefchanges in reference voltage With temperature. In thefspecicembodiments of our Vinvention disclosed herein thisis accomplished .byproviding'. a :resistance in vthe ypotentiometer;'connected across Vtheoutput circuit :of a voltage regulator, thereby altering 'the effectiveelectrical :position of the 'r'oving'terminal of the potentiometer in`accordance Withfthe temperature condi- Itio'ns at the 'source vofreferencevoltage.

H The 'novelfeatures which we believe to be characteristic of ourinvention are 'setforth -Withparticularity in the appended claims. .'Ourinvention itself, however, fboth vas'- to its organization andmethod ofoperation; together :with kfurther :objects 'and advantages thereofymay'bestfbe 'understood by `reference .to the kfollowingdisclosure takennconnectionvvith the accompanying .drawings'in'vvhich: Fig. 1 is ayschematic diagram of .a regulator circuitiiembodying the invention. in'which a resistance having a negative temperature coefiicientxsutilized; and Fig.;2:is a schematic diagram .of an. alternative`regulatorcircuit kin which a resistance having a positiyeftemperaturecoeiiicient is utilized.

"Fig: 1 lsliovvs an electron tube voltage regulator or" 'the abovedescribed type. In this regulator, input terminals I and 2 areconnected-'tocasource of unidirectional electromotive force, terminal' lboeing connected tothe positive side of thesource and fterminal 2 tothenegative` side. Theanode of electron Ydischarge devicer 3 'isf connectedto terminal vrand the cathode connected to positive output terminal .4.Negative'. output terminal 5 connects directly to negative inputterminal 2. Resistance 6, electrondischarge.device 1:, andgasdischargedevice 8 comprise a circuit across-output terminals 4 and 5in'which current flow biases the grid of device 3 to alterthe effectiveresistance thereof. Potentiometer 9 provides a. means for applyinga'preselected portion of `output voltage to the' grid 'of einplierdevicel.

VTheicircuitof Fig; l comprises a feedbackv systemin Which'device 'lreceives gridbias in vaccordance with the dierence -betvveenfthe`vselected portion of output voltage across terminals 4 and 5 and therelatively constant voltage acrossjgas discharge device t. Thisbiasvoltageis amplified in device 'i and applied tobias the gridA oi' device3. Byzchoosing device 'I and device 3, together with resistance' 5, to`have values g-iving'a high degree.v of amplification in thefeedbackpath, rthe dierence -betWeen -output- `voltage across terminals 4 and 5and the desired output voltagefis caused to'be verysmall. despitevariations'in the impedanceacrossterminals 4. and Sand the value ofinput voltage across terminals; |andv .2.

.inasmuch as the regulator ofi Eig. 1 acts to maintain the selectedportion of output voltage at a predetermined value with respect to thevalue of reference voltage at gas discharge device 8, any

changes in the reference voltage are reiiected as corresponding changesin output voltage. Actually, gas discharge tube 8 provides constantreference voltage only at a particular temperature, and if litstemperature is changed, a corresponding voltage change appears atterminals d and 5. For this reason, the circuit of Fig. 1 does notprovide exactly constant voltage but instead provides a voltage varyingin accordance with the ambient temperature at gas discharge tube 8.

In accordance with the embodiment of our invention shown in Fig. 1,auxiliary resistance l is provided between the negative side ofpotentiometer 9 and the negative load terminal 5. This ,resistance isphysically mounted close to gas discharge device 8 so that itstemperature corresponds with the temperature of that tube. In addition,this resistor has a negative coefcient of resistance change withtemperature so that as device 3 heats or cools in accordance withambient temperature the value of resistance ill decreases or increasesaccordingly. Since the total effective grid bias at amplifier device 'lis equal to the diierence between the voltage of gas discharge device Sand the combined voltage across resistance lil and the preselectedportion of the voltage across potentiometer 9, the decreased voltage attube 8 associated with a temperature increase is compensated by acorresponding decrease in resistance it and the voltage thereacrossaccordingly reduced. Conversely, if the temperature of gas dischargedevice 8 decreases, thereby increasing the value of reference voltage,the value of resistance lli increases and the voltage drop thereacrossis correspondingly raised. In either event, the total effective gridbias at device l for a particular output voltage remains constant.

A further modification of our invention is shown in Fig. 2. In thismodiiication, resistance l l is provided between the positive terminalof potentiometer 9 and the positive load terminal 4. By physicallylocating this resistance to partake of the temperature of gas dischargedevice 8, and utilizing a resistance material having a positiveresistance change with temperature, a compensating voltage is providedwhich maintains constant grid bias of tube i despite temperature changesat device 8. In this circuit, an increase in temperature at gasdischarge device 8 causes the Voltage thereacross to decrease while atthe same time the increased value of resistance Il produces acorresponding decrease in voltage across the preselected portion of thevoltage drop across potentiometer 9. Hence the eiective grid bias attube 'l remains unchanged. Operation of the regulator is, therefore,independent of temperature changes at gas discharge device 8.

It will be evident to those skilled in the art that if the source ofreference potential is a battery or other source wherein output voltageincreases with rising temperature, the above described circuits may beapplied except that resistance i9, Fig. l, should have a positivecoefficient of resistance change with temperature, and resistance i I,Fig. 2, should have a negative coeilicient of resistance change withtemperature.

While We have described our invention with reference to a particularvoltage regulating circuit, it will be understood that it may be readilyapplied to other types of regulating circuits whether adapted tomaintain constant voltage across load terminals or to maintain someother characteristic such as motor speed, load current, temperature,etc., constant inasmuch as our invention in its broadest aspectcontemplates the use of a resistance physically located to partake ofthe temperature of the reference voltage source and adapted to provide acompensating voltage which balances the change in reference voltagessociated with temperature variations.

While we have illustrated particular embodiments of our invention, itwill of course be understood that we do not wish to be limited theretosince various modications, both in the circuit management and in theinstrumentalities employed, may be made, and we contemplate by theappended claims to cover any such modiiications as fall within the truespirit and scope of our invention.

What We claim as new and desire to secure by Letters Patent of theUnited States, is:

l. A voltage regulator comprising in combination, a source ofunidirectional electromotive force, a load connected thereto, a sourceof substantially constant reference voltage having decreasing voltagewith increasing temperature, a temperature sensitive resistancemechanically disposed adjacent said source so as to be maintained atsubstantially the same temperature as said source or" reference voltage,said resistance having a temperature coeicient producing decreasingresistance with increasing temperature, a second resistance, meansconnecting said iirst and second resistances in series relation acrosssaid load, and means to control the voltage .of said first mentionedsource in accordance with the difference between the voltage of saidsource of reference voltage and the total voltage across said firstresistance and at least a portion of said second resistance, thereby tomaintain constant the electromotive force at said load, said rstresistance having a resistance change with temperature such thattemperature changes at said source of reference voltage aresubstantially prevented from influencing the voltage output of saidregulator.

2. A voltage regulator comprising in combination, a source ofunidirectional electromotive force, a load connected thereto, a sourceof substantially constant reference voltage having decreasing voltagewith increasing temperature, a temperature sensitive resistancemechanically disposed adjacent said source so as to be maintained atsubstantially the same temperature as said source of reference voltage,said resistance having a temperature coeiiicient producing increasingi'esistance with increasing temperature, a second resistance, meansconnecting said first and second resistances in series relation acrosssaid load, and means to control the voltage of said iirst mentionedsource in accordance with the dilerence between the voltage of saidsource of reference voltage and the voltage across at least a portion ofsaid second resistance, thereby to maintain constant the electromotiveforce at said load, said first resistance having a resistance changewith temperature such that temperature changes at said source ofreference voltage are substantially prevented from innuencing thevoltage output of said regulator.

3. A voltage regulator comprising in combination, a source ofunidirectional electrornotive force a load connected thereto, a sourceof substantially constant reference voltage having increasing voltagewith increasing temperature, a

temperature sensitive resistance mechanically disposed adjacent saidsource so as to be maintained at substantially the same temperature assaid source of reference voltage, said resistance having a temperaturecoecient producing decreasing resistance With increasing temperature, asecond resistance, means connecting said rst and second resistances inseries relation across said load, and means to control the voltage ofsaid first mentioned source in accordance with the difference betweenthe voltage of said source of reference voltage and the voltage acrossat least a portion of said second resistance, thereby to maintainconstant the electromotive force at said load, said rst resistancehaving a resistance change with temperature such that temperaturechanges at said source of reference voltage are substantially preventedfrom iniiuencing the volt- 'age output of said regulator.

4. A voltage regulator comprising in combination, a source ofunidirection electromotive force, a load connected thereto, a source ofsubstantially constant reference voltage having increasing voltage withincreasing temperature, a temperature sensitive resistance mechanicallydisposed adjacent said source so as to be maintained at substantiallythe same temperature as said source of reference voltage, saidresistance having a temperature coefficient producing increasingresistance with increasing temperature, a second resistance, meansconnecting said rst and second resistances in series relation acrosssaid load, and means to control the voltage of said first mentionedsource in accordance With the difference between the Voltage of saidsource of reference voltage and the total voltage across said rstresistance and at least a portion of said second resistance, thereby tomaintain constant the electromotive force at said load, said rstresistance having a resistance change with temperature such thattemperature changes at said source of reference voltage aresubstantially prevented from inuencing the voltage output of saidregulator.

5. The combination, in a voltage regulator, of a voltage source, a loadconnected across said source through an impedance, tWo paths across saidload, one including a constant voltage gaseous discharge device and theother including resistance, means responsive to the difference in 5voltages across said gaseous discharge device and a part of saidresistance to vary said impedance thereby to maintain the voltage acrosssaid load substantially constant, and means to prevent said voltageacross said load from being aiected by variations in voltage across saidgaseous discharge device produced by ambient temperature variations,said means comprising a resistance element included in one of said pathsand positioned closely adjacent said discharge device so as to besubject to the same ambient temperature variations as said gaseousdischarge device, said element having a resistance coeicient varyingtherewith in a direction tending to maintain said difference in voltageindependent of said ambient temperature.

6. A voltage regulator comprising in combination, a source ofunidirectional electromotive force, a load connected thereto, a sourceof substantially constant reference voltage having voltage variationswith temperature changes, a temperature sensitive resistancemechanically disposed adjacent said source so as to be maintained atsubstantially the same temperature as said source of reference voltage,said resistance having a temperature coeflicient producing a resistancechange with temperature change, a second resistance, means connectingsaid first and second resistances in series relation across said load,and means to control the voltage of said rst mentioned source inaccordance with the difference between the voltage of said source ofreference voltage and the voltage across at least a portion of saidsecond resistance, thereby to maintain constant the electromotive forceat said load, said rst resistance having a resistance change withtemperature such that temperature changes at said source of referencevoltages are substantially prevented from influencing the voltage outputof said regulator.

JAMES MOIR. WILLIAM S. GEHT-BAKER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,875,043 Leece et al Aug. 30,1932 2,093,626 Ward Sept. 2l, 1937 2,219,195 Norgaard Oct. 22, 19402,362,562 Kelly Nov. 14, 1944

